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ufunction hook simplified
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@WistfulHopes
WistfulHopes committed Feb 17, 2024
1 parent c173fad commit 92a4a0e
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Showing 2 changed files with 162 additions and 7 deletions.
2 changes: 1 addition & 1 deletion CSharpLoader/include/DotNetLibrary.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -276,7 +276,7 @@ namespace RC::DotNetLibrary
static void Log(LogLevel::LogLevel Level, const char* Message);
};

using UFunctionCallback = void(*)(UObject* pThis, void* parms, void* out_parms, void* return_val);
using UFunctionCallback = void(*)(UObject* pThis, void** parms, void* return_val);

struct CSharpUnrealScriptFunctionData
{
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167 changes: 161 additions & 6 deletions CSharpLoader/src/DotNetLibrary.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -146,7 +146,50 @@ namespace RC::DotNetLibrary
const auto& callback_data = it->second;
for (const auto& [callback, index] : callback_data.registry_indexes)
{
callback(Context, Stack.Locals(), Stack.OutParms(), RESULT_DECL);
auto node = Stack.Node();
auto return_value_offset = node->GetReturnValueOffset();
auto has_return_value = return_value_offset != 0xFFFF;
auto num_unreal_params = node->GetNumParms();
if (has_return_value && num_unreal_params > 0)
{
--num_unreal_params;
}

std::vector<void*> params;

if (has_return_value || num_unreal_params > 0)
{
for (Unreal::FProperty* param : node->ForEachProperty())
{
if (!param->HasAnyPropertyFlags(Unreal::EPropertyFlags::CPF_Parm))
{
continue;
}
if (has_return_value && param->GetOffset_Internal() == return_value_offset)
{
continue;
}

void* data{};
if (param->HasAnyPropertyFlags(Unreal::EPropertyFlags::CPF_OutParm))
{
auto OutParams = Stack.OutParms();
while (OutParams && OutParams->Property != param)
{
OutParams = OutParams->NextOutParm;
}
data = OutParams ? OutParams->PropAddr : nullptr;
}
else
{
data = param->ContainerPtrToValuePtr<void>(Stack.Locals());
}

params.push_back(data);
}
}

callback(Context, params.data(), RESULT_DECL);
}
}
};
Expand Down Expand Up @@ -200,18 +243,130 @@ namespace RC::DotNetLibrary
{
auto& csharp_data = *static_cast<CSharpUnrealScriptFunctionData*>(custom_data);

if (csharp_data.callback_ref == nullptr) return;
if (csharp_data.callback_ref == 0) return;

// Attempt at dynamically fetching the params
uint16_t return_value_offset = context.TheStack.CurrentNativeFunction()->GetReturnValueOffset();

// 'ReturnValueOffset' is 0xFFFF if the UFunction return type is void
csharp_data.has_return_value = return_value_offset != 0xFFFF;

uint8_t num_unreal_params = context.TheStack.CurrentNativeFunction()->GetNumParms();
if (csharp_data.has_return_value)
{
// Subtract one from the number of params if there's a return value
// This is because Unreal treats the return value as a param, and it's included in the 'NumParms' member variable
--num_unreal_params;
}

std::vector<void*> params;

csharp_data.callback_ref(context.Context, context.TheStack.Locals(), context.TheStack.OutParms(), nullptr);
bool has_properties_to_process = csharp_data.has_return_value || num_unreal_params > 0;
if (has_properties_to_process && (context.TheStack.Locals() || context.TheStack.OutParms()))
{
// int32_t current_param_offset{};

for (Unreal::FProperty* func_prop : context.TheStack.CurrentNativeFunction()->ForEachProperty())
{
// Skip this property if it's not a parameter
if (!func_prop->HasAnyPropertyFlags(CPF_Parm))
{
continue;
}

// Skip if this property corresponds to the return value
if (csharp_data.has_return_value && func_prop->GetOffset_Internal() == return_value_offset)
{
csharp_data.return_property = func_prop;
continue;
}

// Non-typed pointer to the current parameter value
void* data{};
if (func_prop->HasAnyPropertyFlags(CPF_OutParm))
{
auto OutParams = context.TheStack.OutParms();
while (OutParams && OutParams->Property != func_prop)
{
OutParams = OutParams->NextOutParm;
}
data = OutParams ? OutParams->PropAddr : nullptr;
}
else
{
data = func_prop->ContainerPtrToValuePtr<void>(context.TheStack.Locals());
}

params.push_back(data);
}
}

csharp_data.callback_ref(context.Context, params.data(), nullptr);
}

void Hooking::CSharpUnrealScriptFunctionHookPost(UnrealScriptFunctionCallableContext context, void* custom_data)
{
auto& csharp_data = *static_cast<CSharpUnrealScriptFunctionData*>(custom_data);

if (csharp_data.post_callback_ref == nullptr) return;
if (csharp_data.post_callback_ref == 0) return;

// Attempt at dynamically fetching the params
uint16_t return_value_offset = context.TheStack.CurrentNativeFunction()->GetReturnValueOffset();

// 'ReturnValueOffset' is 0xFFFF if the UFunction return type is void
csharp_data.has_return_value = return_value_offset != 0xFFFF;

uint8_t num_unreal_params = context.TheStack.CurrentNativeFunction()->GetNumParms();
if (csharp_data.has_return_value)
{
// Subtract one from the number of params if there's a return value
// This is because Unreal treats the return value as a param, and it's included in the 'NumParms' member variable
--num_unreal_params;
}

std::vector<void*> params;

bool has_properties_to_process = csharp_data.has_return_value || num_unreal_params > 0;
if (has_properties_to_process && (context.TheStack.Locals() || context.TheStack.OutParms()))
{
// int32_t current_param_offset{};

for (Unreal::FProperty* func_prop : context.TheStack.CurrentNativeFunction()->ForEachProperty())
{
// Skip this property if it's not a parameter
if (!func_prop->HasAnyPropertyFlags(CPF_Parm))
{
continue;
}

// Skip if this property corresponds to the return value
if (csharp_data.has_return_value && func_prop->GetOffset_Internal() == return_value_offset)
{
csharp_data.return_property = func_prop;
continue;
}

// Non-typed pointer to the current parameter value
void* data{};
if (func_prop->HasAnyPropertyFlags(CPF_OutParm))
{
auto OutParams = context.TheStack.OutParms();
while (OutParams && OutParams->Property != func_prop)
{
OutParams = OutParams->NextOutParm;
}
data = OutParams ? OutParams->PropAddr : nullptr;
}
else
{
data = func_prop->ContainerPtrToValuePtr<void>(context.TheStack.Locals());
}

params.push_back(data);
}
}

csharp_data.post_callback_ref(context.Context, context.TheStack.Locals(), context.TheStack.OutParms(), context.RESULT_DECL);
csharp_data.callback_ref(context.Context, params.data(), context.RESULT_DECL);
}

intptr_t Hooking::SigScan(const char* Signature)
Expand All @@ -237,7 +392,7 @@ namespace RC::DotNetLibrary

PLH::x64Detour* Hooking::Hook(const uint64_t fnAddress, const uint64_t fnCallback, uint64_t* userTrampVar)
{
auto hook = new PLH::x64Detour(fnAddress, fnCallback, userTrampVar);
const auto hook = new PLH::x64Detour(fnAddress, fnCallback, userTrampVar);
hook->hook();
return hook;
}
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